On charge-transfer complexes in the vapor phase

The data on charge-transfer complexes in the vapor phase are analyzed and compared with the data for solutions. An attempt is made to distinguish between the effects of true charge-transfer forces and those attributable to simple van der Waals forces. The complex in the iodine-benzene system in the vapor phase appears to be held together almost solely by van der Waals forces, whereas in other cases the charge-transfer forces contribute in varying degree. Certain inferences are made concerning the mutual orientation of molecules in true charge-transfer complexes, and its effects on the equilibrium constants and absorption intensities. Some remarks on the effect of the complexes on the rate of association of iodine atoms have been appended.